1. Technical Field
The present disclosure relates to complexes of carbon nanotubes or fullerenes with molecular clips containing aromatic side arms. This disclosure also relates to stabilized solutions of these complexes in aqueous or organic solvents. This disclosure is also concerned with the use of these complexes for separation of carbon nanotubes and fullerenes according to their diameters and self assembly of these complexes on particular metal or metal oxide surfaces. This disclosure also relates to use of molecular clips—CNT complexes for selective placement of carbon nanotubes and fullerenes.
2. Background Art
Carbon nanotubes (CNT) are semiconducting or metallic materials that can be used as the ‘channel’ material in field-effect transistors (FETs). One of the most common methods of fabricating CNT FETs starts with depositing nanotubes on an oxide thin film from a liquid suspension. Source and drain contacts are then formed lithographically on the nanotube. The oxide layer is the gate dielectric, and the highly doped bulk Si substrate back-gates the device. A schematic of a CNT FET is shown in FIG. 1. The deposition of CNTs on an oxide surface, followed by lithographic patterning of source and drain contacts, has been successfully used in construction of single CNT field-effect transistors (or mats of CNTs).
The first requirement for solution deposition of carbon nanotubes is a stable solution of carbon nanotubes in an organic solvent or an aqueous solution thereof. There have been many examples of dispersions of carbon nanotubes in aqueous solution using an organic soap, e.g. sodium dodecylsulfonate, in water. Although highly stable solutions of carbon nanotubes in aqueous sodium dodecylsulfonate (DSD) have been reported, the presence of the sodium salt in any electronic device results in adverse electrical effects that is detrimental to device performance.
Other methods of forming stable dispersions of carbon nanotube have been through functionalization of CNTs with long chain organic compounds through carbon-carbon bond formation with a substituted aryldiazonium salt. Functionalization of CNTs via carbon-carbon bond formation destroys the conjugated structure of CNTs and resulting in CNT devices that show significant scattering of electrical charge. These CNTs can not be used as a semiconductor or a metal unless the organic decontamination is removed at very high temperature (500-600° C.).
Another challenge facing the application of CNTs in electronic applications is heterogeneity in CNT diameters and hence in the band gap of semiconducting CNTs in samples prepared by known methods. For electronic applications it is mostly desirable to use CNTs with a narrow distribution in size (diameter) to obtain devices with reproducible electronic properties.